U.S. Pat. No. 4,552,772 discloses a method for preparing a pre-cooked pasta product suitable for rapid cooking without using artificial preservatives. This process comprises boiling the pastas and washing said pasta with water, the improvement comprising immersing the boiled pastas in an aqueous solution containing at least one of citric acid and lactic acid, and table salt, then packaging and heat sterilizing the pastas which have been immersed, said aqueous solution having a pH such that the pH of the boiled pastas, after immersion, is about 3.9 to 4.3. However, the pasta pieces tend to stick together after heat processing and are difficult to separate, which is not convenient for consumption.
French Patent No. FR2502907 discloses the a process for the production of pre-cooked pasta product that comprises treating raw pasta product in the following stages: pre-cooking, preferably in acidified water, to give the product a moisture content sufficient for subsequent sterilization; cooling, preferably in a current of cold, acidified water; draining off excess water; oiling with a vegetable oil e.g., by vaporization; introducing into a flexible container; reduction and uniformization of thickness; sealing the containers in vacuum; heat sterilization of scaled containers. The use of vegetable oil prevents the pasta pieces from sticking together but, as a result, the pastas have an oily appearance and, because of the sterilization treatment, they have a less than desirable texture.
European Patent No. EP0489811 discloses a process for preparing an acid-stabilized pasta that comprises cooking the pasta in an aqueous acid solution or suspension having a pH of less than 6, and containing a polymeric food-acceptable acid in which the monomer unit has a molecular weight of about 190 g/mol.
European Patent No. EP0626137 discloses a pasteurized, shelf-stable, uncooked or partially cooked, moist pasta product packaged in a sealed container. The pasta product, which is partially dried after the acid treatment, is not treated with oil, has a moisture content from 15 percent to 38 percent, and a pH below 4.6.